To facilitate the detection of postcibal gastroesophageal reflux (GER), we have constructed an infant formula from modular carbohydrate, fat, and protein components with a pH of 4 and a nutrient composition identical to standard infant formula, in comparison to standard infant formula and sugar solutions, this pH-adjusted formula demonstrates a significantly greater amount of gastroesophageal reflex during the first postcibal hour. We speculate that the greater caloric density and slower gastric emptying of regular infant formula promotes greater gastroesophageal reflux than is observed with regular dextrose feedings. This effect is obscured unless the pH of the formula is adjusted. Use of this weakly acid formula in conjunction with postcibal esophageal pH probe recording facilitates the detection and, during simultaneous apnea monitoring, potential association of symptoms with postcibal gastroesophageal reflux.